The difference between Vue3 and Vue2: better front-end engineering

The difference between Vue3 and Vue2: better front-end engineering

In recent years, Vue.js has become one of the popular frameworks for front-end development. As a fast, flexible, and easy-to-use front-end framework, Vue.js brings us a lot of convenience during the development process. In the recently released Vue.js 3, we can see that it has better front-end engineering features than the previous version Vue.js 2. This article will use code examples to compare the differences between Vue.js 3 and Vue.js 2, and analyze their impact on front-end development.

1. Composition API

In Vue.js 3, a new composition API (Composition API) is introduced to replace the previous Options API. Through this new API, we can organize and reuse code more conveniently, making the code easier to maintain and understand.

The sample code is as follows:

Options API of Vue.js 2:

export default {
  data() {
    return {
      count: 0,
    };
  },
  methods: {
    increment() {
      this.count++;
    },
    decrement() {
      this.count--;
    },
  },
};

Composition API of Vue.js 3:

import { ref } from 'vue';

export default {
  setup() {
    const count = ref(0);

    function increment() {
      count.value++;
    }

    function decrement() {
      count.value--;
    }

    return {
      count,
      increment,
      decrement,
    };
  },
};

As you can see, In the Composition API of Vue.js 3, we use the setup function to declare and define data and methods. Use the ref function to create responsive data, and use the return statement to expose the data and methods that need to be provided to the template.

2. Better TypeScript support

In Vue.js 3, the support for TypeScript is more complete. By typing reactive data, we can catch many potential errors during development. This makes us more comfortable when writing and maintaining code.

The sample code is as follows:

Options API of Vue.js 2:

export default {
  data() {
    return {
      name: '',
      age: 0,
    };
  },
  methods: {
    submit() {
      if (this.name && this.age) {
        // ...
      }
    },
  },
};

Composition API TypeScript of Vue.js 3:

import { ref } from 'vue';

interface User {
  name: string;
  age: number;
}

export default {
  setup() {
    const name = ref('');
    const age = ref(0);

    function submit() {
      if (name.value && age.value) {
        // ...
      }
    }

    return {
      name,
      age,
      submit,
    };
  },
};

By pairing# By defining the types of ##name and age, we can reduce the occurrence of type errors during the development process.

import Vue from 'vue';
import App from './App.vue';

new Vue({
  render: (h) => h(App),
}).$mount('#app');

import { createApp } from 'vue';
import App from './App.vue';

createApp(App).mount('#app');

createApp function to create a Vue instance instead of directly introducing the Vue class. This change allows the required modules to be imported on demand during packaging, improving the quality of the packaged code.

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